Microvascular Diameter Changes during Local Blood Flow Regulation: Independence of Changes in PO2
The flow of blood to tissues is largely regulated by the contractile activity of the vascular smooth muscle of the arterioles and precapillary sphincters in the microcirculation. It has long been recognized that there is a feedback mechanism between tissue and vessel which modulates vascular smooth muscle contraction. One of many substances which has been proposed as a mediator of this regulation is oxygen (1,2). It is apparent that oxygen might be a regulator either via its action, if any, directly on the smooth muscle cells themselves or alternately by an indirect mechanism which initially alters parenchymal cell function. It is usually assumed that oxygen acting via an indirect mechanism causes altered release of a vasodilator metabolite which then reduces the contraction of the vascular smooth muscle (1,2).
KeywordsVascular Smooth Muscle Contractile Activity Diameter Change Cheek Pouch Hamster Cheek Pouch
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